Release of O-glycans by Enzymatic Methods

Abstract

Endo-type glycosidase is an indispensable tool for obtaining an intact sugar chain from glycoprotein and also to prepare intact deglycosylated proteins. To release the O-glycan sugar chain from mucin-type glycoproteins, endo-α-N-acetylgalac tosaminidase (endo- GalNAc-ase, glycopeptide α-N-acetylgalactosaminidase, EC 3.2.1.97) is usually used. An enzyme from Streptococcus (Dipplococcus) pneu monia is now commercially available as O-Glycanase, although its application was fairly restricted due to its narrow substrate specificity. To overcome its narrow substrate specificity, development of a new type of endo-GalNAc-ase having broad substrate specificity was expected. We found two types of endo-GalNAc-ase activities in Streptomyces sp. OH-11242; however, we are still awaiting confirmation of the reproducibility of enzyme pre paration and its substrate specificity by other researchers (Ishii-Karakasa et al. 1992; Tanaka et al. 1998). Because the secretion of sialyl mucin-type oligosaccharide in normal human urine has been reported, such endo-GalNAc-ase is thought to be present in the natural world (Parkkinen and Finne 1987).